void main(List<String> args) {
  print("泛型约束");
  List<String> list=["1","2","3"];
  list.forEach((item){
    print(item);

  });
   
   Map<String,dynamic> m ={
    "alipay":'阿里巴巴',
    "wechat":"微信",
    "bytedance":"字节跳动",
    "1":3
   };

   print(getNameById<dynamic>("别急", 123));
}

T getNameById<T>(T value1,T value2){

 return value1;

}